Machine-tool drive



Jan. 13, 1931. H. ERNST 1,788,761

MACHINE TOOL DRIVE Filed Feb. 9, 1927 2 Sheets-Sheet 1 ll l w m 2% -A ,21/ I I w iw Jan. 13, 1931. H. ERNST MACHINE TOOL DRIVE Filed Feb. 9,1927 2 SheetsSheet 2 WM UM \N tween cutter and work being transmitted inPatented Jan- 13, 1931 UNITED-STATES HAN "PATENTOFFICE ERNST, OICINCINNATI, OHIO, ASSIGINOR '10 CINCINNATI MILLING HA- 7 CHINE COMPANY,01 CINCINNATI, OHIO, A CORPORATION OF OHIO .IIACHINE-JIOOL DRIVEApplication filed February a, 1927. Serial No. 160,985.

This invention relates to improvements 'in machine tool drives and hasparticular reference to a novel and improved form of drive mechanismparticularly adapted for use in connection'with'mil'ling or othercutters, designed-to have an intermittent engagement with the work.

ne of the objects of the present invention is the provision of a driveembodying a vibration dampener which will prevent the vibrations ofintermittent engagement bea positive manner to the gear train, thussetting up recurrent strain, chattering, and the li e 1n saidmechanism.r

A further object of the present invention is the provision of animproved self-contained hydraulic shock absorbing mechanismfor use inpower transmission. T

Other objects and advantages of present invention should be readily aparf h therefore to obviate these difficulties. T1118 invention.

Another object of the resent invention is the provision of a sel-c0ntained mechanism of the character mentioned which will automaticallybuild up a cushioning pressure which will counterbalance the resist ancemomentarily or otherwise exerted against the actuated member.

out by references to the following speci cationtaken in connection withthe accomthat' I may make any modifications in scope of theaipp'endedclaims, without departing from or exceeding the spirit of the Figure 1is an, elevation of a machine having my improvementsflembodied therein.

Figure 3 isa section on; line 3+3 of Figure2.

Figure 4 is an enlarged sectional view pump member's, and, Figure 5 isan enlarged section through the compensating pistons, position thereof.

In the drawin s the letter A designates the base of a mllling'machine'having the column B supporting the power transmission transmittinggears.

Figure 2 is a sectional; view on the line' 2-2 of Figure 1.

gearing designated as an entirety by the reference character C.This-mechanism is adapted to supply driving force-tothe cutter spindle Dfor actuationthereo f.

Prior to my invention it has been-customary in mechanism ofthischaracter to employ suitable transmission m'eans such as the 10 on shaft11 for actuation of the cutter. When this is a direct gear drive,however,'- certain disadvantages are r encountered due tothe-fact' thata milling eutter'for example, is formed with a plurality of teeth whichconsequently consecutively, rather than simultaneously enga e the workduring the feeding operation wit the result that there is an irregularapplication of power through the drive gearing to the cutter spindle,spindle to jump ahead between. cuts and the temporary retardance, as anew tooth operatively engages the work. At certain feeds andspeeds thisproduces considerable ;vibration or chatter in the driving mechanism andundue strain on the several power Also, this intermittent -action .tendsto render the entire machine quitemoisy in operation.

It i s'thejpurpose of the present invention is 1 accomplished bysecuring on spindle D a sleeve 12 having a flange 13. Loosely mounted-onsaid flange 13 is a worm gear 14 adapted to mesh with the worm 10. This13 and secure the gear peripherally thereon due to the tendency, of thefor movement relative thereto. The parts 15 i and 17' are further;connected by cross pins 18 extending. through slots 19 in the flange'13, p v

The flange 1'3 contains the vibration dampening or-yielding' couplingmechanism for regulating the drive connection between showing-a'shift'edthe worm andspindle.

mechanism includes the pair of similar oppositely 'disposed cylinders20, there being one of:.these cylinders for each pin 18. As theirstructure is identical, a description of one W111.

I flange 13 as will be clearly understood by reference to Figures 2 and3. As the springs 23 exert equal pressure against the pistons theynormally tend to keep the pin 18 in a centralized position as indicatedin Figure 3.

To further aid in proper positioning of the pistons, use is made of oilor other fluid pressure introducible into the cylinder as throughpassages 26 and ports 27in the cylinder walls. The pistons themselvesare provided with peripheral grooves as in dicated at 28 and have incommunication with said grooves the ports 29 for introducing pressureinto the hollow interior 30 of the pistons and between the pistons andends of the cylinders. The cylinders are additionally provided with theoutlet ports 3]. controlled by check valves 32, these ports being sodisposed that under normal conditions the. fluid under pressure may passaround groove 28 and through tapered outlet 33 into exhaust port 31 andthence escape through sleeve nut 34 adjacent the check valve, so thatundue pressure will not be built up in the cylinders. The normal].cushioning pressure in the cylinders tending to retain the istons innormal 0 ntralized position therefore depends on the r istance of thecheck valves 32.

However, whenthe resistance'to rotation of spindle D exceedsthe pressureback of the right hand piston of- Figure 5, assuming that the worm gearis being rotated in a clockwise direction, the pin 18 will move towardthe right, together with the gear, thus causing a movement of the pistontoward the right as is shown in Figure 5. As

the piston is moved to the right, ports 27 and 29 will still remain incommunication, allowing pressure to pass to the hollowint'erior 30 ofthe piston, but outlet 33 will be shifted away from port 31, so that thepressure can no longer escape through the right hand check valve 34.'Consequently, pressure will be built up within the piston and cylinderat the right hand side tending to reshift the piston toward the left andwith it the pin 18. At the same time that the right hand pistonmoves tothe right the combined :Rtion of the pressure in the left hand cylinderand expansion of sprin 23 will correspondingly shift piston 21. As thispiston shifts its port 29 will move out of alinement with port 27 andthe solid end of thepiston will serve as a closure for this port, sothat the built up pressure will not be active in the left hand end ofthe cylinder. Also, the groove 28 will be brought into alinement withits relief port 31 so that at any time pressure within the left hand endof the cylinder may pass out through port 27, groove 28 and relief port31 tending to reduce the pressure in this end of the cylinder. Thecombined result of this action is that the greater theresistance torotation of spindle D and consequent shifting of piston 22 to the right,the greater will be the shutting off of escape of pressure from theright hand end of the cylinder and consequent building up of resistantpressure into this end of the cylinder, coupled with reduced pressure atthe opposite end of the cylinder, so that there is an hydraulic.

cushioning efiect preventing the vibrations from intermittentresistances being transmitted direct to the driving gears.

This resisting pressure may be created in any desired manner, butpreferably use is made of a self-contained pump mechanism and pressuredistributing system such as particularly illustrated in Figures 2, 3 and4 of the drawings. This pressure creating and distributing systemincludes'the interconnecting passages 35- and a plurality of similarpump members, one of which is shown 'insectlon in Figure 4. This membercomprises the pump cylinder 36 having slidable therein plunger 37 havingan inlet port 38, passage 39 and check valve 40. A spring 41 outwardlyactuates this plunger. Beyond the compression chamber 42 is a restrictedport 43 controlled by an outlet valve 44 controlling flow of fluid intothe chamber 45 in communication with} theinterconnecting ports 35. I g aThe several ends of the l-ungers 37 proect into grooves 46 in the faceof the collar 47 rotatably supported through thrust bearmg 48 in the capmember 49 of the casing 50 of the present mechanism.

By reference to Figure 2 it will be noted that the thrust bearing 48 isdisposed in.-

tilted relation to the axis of spindle D and with one side nearer flange13 than is its As a result, on rotation of the. shaft and flange theengagement of the opposite side.

plungers with collar 47 will successively press the plungers inward ontheir downward movement producin the compression stroke of the, pump mecanism, while on the upward movement the springs 41 will force theplungers outward for the suction stroke. It will be noted that casing 50forms an oil reservoir in which gear 14 and its driving worm 10 operateand thatthe flange has a plurality of outwardly extendin radial passa s51 communicating throng ports 52in t e pumpcyli'nders and effectthereof;

From the foregoing description it will fursage 51 is below thehorizontal position and consequently submerged in oil, even though thechamber be not over half full. Reverse flow of the oil being preventedby the check. valve 40 as the plunger is forced inward,

the oil in chamber 42 is ejected past valve 44 into chamber 45 anddistributing passages 35 to the two pistons equally, in the event thatpin 18 is centrally supported thereby. However, in the event that thepin is not so supported, but the parts are in the position shown inFigure 5, flow of the fluid to the inwardly shifted piston is cut-offand escape of fluid from the outwardly shifted piston is also cut offwith the result that the entire pressure generated by the plurality ofplunger pumps is effective within the cylinder driving force which hasbeen resisted. Consequently, the greater the resistance pressure themore entirely escape of this pressure is shut off and consequently theheavier the pressure which will be built up back of.

the piston tending to reshift it to normal position. it will thus beseen that on uneven or intermittent resistance to constant andunfluctuating drive of pin 18, the additional force necessary tocounteract this resistance in place of being effected directly throughthe driving gear train with a hammering action, is initially taken up bytheQpiston and built up by the pressure within the piston, so that thegear 14 itself may have a constant and steady movement irrespective offluctuations in position of the driving connections or ins 18.,Thepiston mechanism just described therefore serves to dampen thesevibrations and prevent regenerative .ther-be noted that ,themechanism-just described is an entirely self-contained propositionoccupying substantially no greater space ,than would normally beoccupied by "the worm gear alone, but that within this space it containsnot only the equalizing drive resisting either jumping ahead or re-':tarded, movement of the spindle, but also is l a selfscorfgtained pumpmechanism actuated by' rotati'en 50f the spindle to satisfactorilysupply the desired" resisting pressure in a simple and effectual manner.

I'claim 11. A power drive,.including a prime mover and aspindlefa'ctuable therefrom, anddrive connections interlhediate theri'me mover and spindle, ineluding;a slotte member associated with oneof isa'i'd parts, a'drive connection loosely engaged. intheslot, amotion limiter adjacent the slot, and hydraulic means for building upthe resistance of the motion limiter.

2. A power drive, including a prime mover and a spindle actuabletherefrom, and drive connections intermediate the prime mover andspindle, including a slotted member associated with one "of said parts,a drive connection loosely engaged in the slot, a yieldable motionlimiter adjacent the slot, and hydraulic means for buildin up theresistance of the yieldable motion limiter.

3. A power transmission mechanism, including a prime mover and aspindle, a power transmission line connecting said parts for actuationof the spindle, said transmission includ ing interengaged fixed andyielding abutments, and hydraulic means for building up the resistanceof the yieldable abutment.

4. A power transmission, including coaxial rotary member's, means forrotating one ofsaid members, means for driving theother membertherefrom, including a fixed abutment, a pair of spaced abutmentsoppositely engaging the fixed abutment, resilient means independentlyinwardly urging said abutments, and additional means jointly inwardlyurging the movable abutments.

5. A power transmission, including coaxial rotary members, means forrotating one of said members, means for driving the other membertherefrom, including a fixed abutment, a pair of spaced abutmentsoppositely engaging the fixed abutment, resilient means independentlyinwardly urging said.

positely engaging the xed abutment, resilient means independentlyinwardly urging said abutments, additional means jointly inwardly urgingthe movable abutments, and automatic means for building up theresistance of either, of the movable abutments proportional to the.-pressure of the fixed abutment thereagainst, said means includingpressure cylinders; adjacent the movable abutments, and means actuatedby movement of'the abutments for varying the flow of actuating fluidinto said cylinders.

7. A drive of the character described, in-

cluding a spindlegand aprime mover therefor, and atransmission"intermediate said parts, including a pair of coaxial rotarymembers, a fixed abutment carried by one of said members and capable oflimited movement as respects the other member, and'means on said othermember for controlling the lim-' ited movement, including a double endcylinder, a pair of pistons mounted in the ends of the cylinder, theabutment of the other member projecting between said pistons, means forcontrolling the actuating pressure within opposite ends of'the cylinder,including inlet and outlet ports and portions on the pistons selectivelycontrolling the flow of actuating fluid through the ports as the pistonsare shifted by engagement with the abutment. V

8. A power transmission drive, including coaxial independently rotatablemembers, and means coupling the members for joint rotation, including aplurality of laterally projected abutments on one of the members andvibration dampening units for engagement with each of said projectionscarried by the other member for coupling the parts, said units eachcomprising a cylinder centrally receiving the projection and spacedpistons in the cylinder oppositely engaging the abutment, centralizingsprings for'forcing the pistons inward in the cylinders, a jointpressure supply pipe for introducing actuating fluid into opposite endsof the cylinder for shifting of the pistons therein, and valve portionson the pistons controlling the flow of fluid into the cylinder ends. 9.A power transmission mechanism, including driving and driven'members, afixed abutment carried by one of said members, a shiftable abutmentcarried by the other member for interengagement with the first abutment,and hydraulic means actuating the shiftable abutment in the direction ofthe fixed abutment with a pressure proportional to the resistance tojoint movement ofiered by the fixed abutment.

10. A power transmission mechanism including a prime mover and spindleactuable l thereby, a power transmission intermediate said parts, a pairof inter-engaged members in the transmission, a plurality ofcircumferentially spaced abutment pins carried by one of said membersparallel to the axis thereof opposing abutments engaging; each abutmentpin and carried by the. ot er of said members, means yieldingly urgingsaid second abutments'into engagment -with their respective abutment inswhereby said onposing abutmentsmay shift to absorb'shocks in thetransmission llne.

11. A power transmission including coaxial rotary members, one of whichis slipported on the periphery of the other for inde endentjrotarmovement means'carried one of the members reventin independent lateralmovement etween t em said means also supporting a pluralit of abutments,a plurality of pairs of yiel able plungers carried; by the other memberengaging opposite sides of each abutment forming a lost motion drivingconnection whereby the transmission of vibrations from the driven memberto the driving member will be prevented.

12. In a power transmission, coaxial rotary members, comprising a rotarydisk member having the other member journaled on its periphery, flangesformed on the outer member for engaging the opposed faces of the disk,driving pi'ns extendin through slots in the disk and fixed at each endin ,the flanges forming a lost motion driving connection between the twomembers, resilient means in the disk engaging opposite sides of the pinsto centralize them in the slots, and limit the amount of lost motionbetween the parts.

13. A power transmission including a driven disk member, a drivingmember journaled thereon havingflanges engagin opposite faces of thedisk, driving pins xed in. the flanges and extending through slots inthe disk, chordal bores in the disk member intersecting the slots,spring pressed centralizing plungers in the bores engaging opposed sidesof the pins to form a resllient driving connection between the members.

'14. A power transmission having concentric members capable of relativerotation hydraulic pressure connected to said cylinders for controllingthe yielding connection.

.ylel ing, driving connection and a source of v 15. A power transmissionincluding co- 4 axial rotary members, means for rotating one ofs'aidmembers, means for drivin the other member therefrom including a xedabut ment, a pair of spacedabutments oppositely engaging the fixedabutment, resilient members independently inwardly urging saidabutments, additional means to jointly maintain a normal inward pressureon said abutments and automatic means to increase said pressure on themovable abutments proportional to the pressure of the fixed abutmentsthereagainst.

16. A power transmission mechanism in- I cluding a driving and drivenmembers, a

housing enclosing said members, drive connectlons mtermedlate saidmembers including a hydraulic vibration dampener, a selfcontainedhydraulic system in said housingconnected to said dampener including a,

reservoir, a pump, means foractuating. the

.pump from one of said members for supplying fluid pressure to saiddampener and means to return the exhaust fluid vtherefrom to thereservoir.

17. A power transmission including a driving and a driven member, ahousing enclosing said members, means coupling the members 'for jointrotation including hydraulic vibration dampening units, hydrau licpressure supply means therefor including a plurality .of axiallyparallel plungers, eccentric means for actuating said plungers andchannels interconnecting said plungers with said units for jointoperation.

18. A power transmission including coaxial independentlyrotatablemembers, 'an abutment fixed on one of said members, resilient plungersmounted in the other of said members engaging opposite sidesof saidabutment to form a driving coupling, hydraulic cushioning means for eachplunger including cylinders having intake and exhaust ports, a source ofpressure therefor, means on the plungers to control the ports of theirrespective c linders whereby e ual pressure will, be malntained in thecylinders when the abutment is in v normal position and differentialcentralizing pressures-will be created therein when the abutment movesfrom normal position.

In testimony whereof I; afiix my signature. v HANS ERNST.

